This invention relates to a new and useful apparatus for testing heads or blocks of internal combustion engines for leaks from the water passages of the blocks or heads.
The heads of internal combustion engines, and particularly those of large diesel engines, are extremely complex structures which have numerous internal coolant, air, or fuel mixture passages. During operation leaks and cracks may develop in the walls of the head which separate the many internal cavities, and if this occurs a detrimental intermixing of coolant, gas, fuel, antifreeze, lubricating oil and other additives can occur. Regularly scheduled spectophotometer analysis of oil samples from such engines indicates the seriousness of leakage and when engine repairs are in order, but when this is known the leaks are still very difficult to locate in practice.
The engine head must be removed from the engine and the openings which connect the internal coolant cavities in the head with the remaining cavities in the engine block must be plugged, and either compressed air or hot water under pressure must then be introduced to the coolant cavity in an attempt to locate any cracks or leaks between the coolant cavity and any of the other cavities or passages in the engine head.
Engine heads come in many different sizes and in numerous different patterns of cavities, passages, and ports, so sealing all of the necessary ports and openings requires a variety of plates, plugs and the like.
The problem of locating leaks and cracks in the engine heads is compounded by the fact that some leaks show up only when the cavity is filled with water or other coolant at relatively high temperatures and under a pressure comparable to that at which the system operates in service. It is both dangerous and difficult to initially locate leaks and cracks in the head by means of hot water under pressure since a bad crack can spray scalding water around the test area.
One attempt to provide an engine head test stand is found in U.S. Pat. No. 3,608,369. In this patent the engine head is supported by a frame which is pivotably mounted on folding legs, similar to those of a saw horse, with a pressure actuated hold down means for engaging the top side of the engine head. A plurality of upstanding sealing elements are provided on the support for sealing the openings in the engine head while a liquid conduit is carried on the hold down means for sealing the inlet opening of the engine head when the pressure means is actuated. The conduit carried on the hold down frame, automatically aligns itself with the water inlet opening on the engine head to circulate water through the engine head. A pair of valves are provided to permit escape of air in the engine head upon the initial introduction of water into the coolant chamber of the head. The test stand permits the engine head support to be rotated manually for inspection. The test device shown in this patent is adequate for small engine heads but is cumbersome for the heavy ones and requires considerable effort in sealing up all of the openings in the engine head. Furthermore, the head must then be rotated manually while the operator tries to inspect the head at the same time. This is difficult when heavy engine heads are tested. Furthermore, the pressurized hold down means is centered in the rack and may or may not effect complete sealing throughout the length of the hold down frame.
Another approach to providing a portable universal apparatus for use in pressure testing engine heads and blocks is found in U.S. Pat. No. 4,157,028. In this device the engine head is mounted or supported on a frame and a plurality of sealing members are placed over all of the surface openings of the cylinder head or block, leading to the cooling jacket. Retaining bars are then manually placed over these sealing members and extend longitudinally of the engine head. A plurality of clamping units are then attached directly to the engine head and apply clamping pressure to the clamping bars in a direction to effect airtight engagement of the sealing members with the surface openings of the cooling jacket. While this device may be adequate for some engines, it is very slow and cumbersome since each of the retaining bars must be individually clamped, by screwing the clamping members down with wrenches or the like. Furthermore, no provision is made for rotating the support for the block or head in this patent.
Still another approach for solving this problem is found in U.S. Pat. No. 4,617,824. In the device shown in this patent, clamping plate cross bar members, clamping members connected to the cross bar members, and clamping screws threaded onto the clamping members, clamp the clamping plate towards the cross bar members, thereby compressing the water passage port sealing plugs positioned between the surface of the cylinder head and the clamping plate, to seal the water passage ports. An air pressure source, a liquid source, and a pump are connected to a diversion valve, and an outlet of the valve supplies air or liquid under pressure as selected to the cylinder head inlet tubes at a water passage port. The cylinder head outlet tubes with an outlet valve are connected to another water passage port. The apparatus disclosed in this patent is effective but very cumbersome and slow in utilization. Furthermore, heavy engine blocks or heads are still very difficult to handle in this device.
Another approach for testing engine blocks or heads is found in U.S. Pat. No. 3,360,984. This patent discloses an apparatus for testing engine cylinder heads which includes adjustable rails for providing a support for manually operated clamps having slidable adjusting movement longitudinally and transversely of the supporting rails, so as to position an associated pressure applying screw in operative relation with the underlying closure member for a port opening in the cylinder head being tested. In an alternative arrangement the clamp includes a toggle mechanism for swinging the pressure applying screw into and out of its operative position of use. In this device each of the closure members must be separately and independently adjusted and closed as with some of the other approaches this is a very time consuming, slow process.
Still another approach is found in U.S. Pat. No. 3,973,429. This patent discloses apparatus for testing engine heads of various sizes for fluid tightness of the internal cavities in a head which communicates with ports in the fire deck surface of the head. A universal mounting frame for the cylinder head is rotatable on a longitudinal pivot axis to position the head with its fire deck surface at any orientation relative to the axis. The device includes longitudinal support rails, positioned above the water ports and spring loaded stopper means and fluid supply and venting members which are longitudinally adjustable on the rails for alignment with the ports. The support rails then are moved down manually to push the entire array of stoppers and fluid couplings into sealing engagement with the fire deck surface and the rims of the ports. Again, this device is cumbersome in use and time consuming.